Appliances equipped with remote control capability are now commonplace, and have proved very popular as they enable the operator of the appliance to effect changes in the operation of the appliance without having to come into physical contact with it. For extra convenience, modern remote control systems do not require an electrical connection between controller and appliance, signalling being achieved by means of suitably-modulated ultrasonic, radio-frequency or infra-red energy. Functions achievable using appliance remote controls include selection of tracks to be played from a compact disk, starting or stopping recording of a video tape recorder, selection of channel on a television receiver, and so on.
Although prior-art infra-red or ultrasonic remote control schemes operate satisfactorily over small distances, usually within the same room as the controlled appliance, it is not possible to operate appliances over great distances. For example it is not possible to start a video recorder from an office several kilometers distant.
Some appliances have been made utilising radio remote control, which permits operation over larger distances, but ultrasonic or infra-red systems are almost universally are far more popular as these systems do not suffer the problem of interference between controllers which often occurs using a radio system. As a result, it is not possible to control the majority of appliances over large distances using the supplied controller.
The present invention overcomes this limitation, providing means and method for controlling commonly-available appliances over large distances without need to modify the appliance.